PRINCIPLE AND ILLUMINATION OF RIVER BASIN UPSTREAM-DOWNSTREAM SUCCESSIVE EVOLVING WATER ENVIRONMENTAL KUZNETS CURVES

Xin’an River Basin,Pearl River Basin,and the Yangtze River Basin were taken as study areas to make multi-scale analysis of Water Environmental Kuznets Curve(WEKC).Relationships between waste water discharge and per Capita GDP of provinces in a river basin were plotted in a figure.Through empirical analysis of WEKC in different regions from small to large scale watersheds,it could be discovered that the WEKC curves roughly follow a principle of repeating step by step from downstream to upstream districts.The curve experienced in the downstream usually reoccurs in the upstream later.The principle is evident especially when there are obvious disparities among development levels of the upstream and downstream.The main reason for this principle is possibly that economic development in downstream areas is generally earlier than the upstream.Consequently,the downstream areas usually possess stronger environmental protection capacity.So the downstream reaches the peak value of WEKC earlier than the upstream.The principle contributes to further understanding of the importance of upstream water resources protection.With background of West Development and Middle Rising Policies,this discovery also illuminates that upstream environmental protection capacity should be strengthened with supports of the country and downstream areas to promote entire and long term watershed protection.